The present invention relates generally to the field of antireflective coatings for use in fabricating semiconductor devices. More particularly, it relates to antireflective coatings formed from dyed siloxane resins.
Photolithography is a known technique in the art of semiconductor fabrication. In a typical photolithography process, a semiconductor wafer is coated with a barrier layer, aka. an anti-reflective coating (ARC) layer. Thereafter, a photoresist layer is coated on the ARC layer. The photoresist/ARC/semiconductor wafer is then brought into proximity to a source of electromagnetic radiation (EM), typically ultraviolet light (UV) having a wavelength from about 150 nm to about 300 nm, and a mask is interposed between the EM source and the photoresist/ARC/semiconductor wafer. The mask is generally opaque to the wavelength of EM used, but has transparent regions defining a desired pattern to be imparted to the photoresist layer.
When the source emits EM, the mask allows exposure of EM to particular and user-defined regions of the photoresist layer. Both positive photoresists and negative photoresists are known. In a positive photoresist, the regions of photoresist exposed to UV, as well as the regions of the ARC layer thereunder, will be sacrificed during subsequent developing steps. In a negative photoresist, the regions of photoresist which are not exposed to UV, as well as the regions of the ARC layer thereunder, will be sacrificed during subsequent developing steps.
Regardless of the details of the photolithography process, an ARC layer desirably has several properties. One property is a relatively high extinction coefficient, i.e., a relatively strong ability to absorb the wavelength of EM used, rather than reflect the EM up to the photoresist layer. A second property is a relatively low resistance to liquid stripping agents, such as diluted hydrofluoric acid, in order to more quickly and easily be removed after photolithography and minimize the extent of damage by a stripping agent to the low-k dielectric material on a wafer.